Update problem.ja.md
Update problem.ja.md

「拡張子は二つ目の引数です」has some ambiguities. 「拡張子は二つ目の引数で指定します」is clear.
However,「アプリの一つ目の引数は」and「（アプリの）二つ目の引数で」make a couple and even better.
sergiorgiraldo/learnyounode,hsidar/learnyounode,michaelgrilo/learnyounode,zhushuanglong/learnyounode,yous/learnyounode,yous/learnyounode,chechiachang/learnyounode,marocchino/learnyounode,akashnimare/learnyounode,runithome/learnyounode,chechiachang/learnyounode,keshwans/learnyounode,pushnoy100500/learnyounode,soujiro27/learnyounode,thenaughtychild/learnyounode,sergiorgiraldo/learnyounode,zpxiaomi/learnyounode,metakata/learnyounode,maksimgm/learnyounode,AustenLR/learnyounode,metakata/learnyounode,amandasilveira/learnyounode,walhs/learnyounode,kishorsharma/learnyounode,kishorsharma/learnyounode,RoseTHERESA/learnyounode-1,soujiro27/learnyounode,CNBorn/learnyounode,marocchino/learnyounode,amandasilveira/learnyounode,lesterhm/learnyounode,noikiy/learnyounode,aijiekj/learnyounode,JonnyCheng/learnyounode,kmckee/learnyounode,RoseTHERESA/learnyounode-1,Gtskk/learnyoupython,andrewtdinh/learnyounode,esmitley/learnyounode,ElTomatos/learnyounode,thenaughtychild/learnyounode,AydinHassan/learnyounode,pushnoy100500/learnyounode,Yas3r/learnyounode,hsidar/learnyounode,keshwans/learnyounode,ralphtheninja/learnyounode,Gtskk/learnyoupython,ElTomatos/learnyounode,aijiekj/learnyounode,Gtskk/learnyoupython,piccoloaiutante/learnyounode,jojo1311/learnyounode,noikiy/learnyounode,runithome/learnyounode,kmckee/learnyounode,andrewtdinh/learnyounode,zhushuanglong/learnyounode,AustenLR/learnyounode,JonnyCheng/learnyounode,AydinHassan/learnyounode,PibeDx/learnyounode,esmitley/learnyounode,PibeDx/learnyounode,akashnimare/learnyounode,michaelgrilo/learnyounode,jojo1311/learnyounode,jqk6/learnyounode,ralphtheninja/learnyounode,lesterhm/learnyounode,piccoloaiutante/learnyounode,5harf/learnyounode,zpxiaomi/learnyounode,5harf/learnyounode,maksimgm/learnyounode,CNBorn/learnyounode,Yas3r/learnyounode,jqk6/learnyounode,walhs/learnyounode